问错误: fortran中不可分类的语句

EN

program test
! integer m,n,r,i
double precision x(2),y(3),z(4)
x=(/2.0,1.0/)
y=(/1.0,2.0,1.0/)
call polymul(x,2,y,3,z,4)
print *,z
 end

subroutine polymul(x,m,y,n,z,r)
! polynominal multipy
integer i,j,k
do i=1,r
z(i)=0.0
end do
do i=1,m
  do j=1,n
    k=i+j-1
    z(k)=z(k)+x(i)*y(j)
  end do
end do
end